(1) Field of the Invention
This invention relates to a color camera that is used in TV-studio camera systems, consumer VCR-camera systems, surveillance camera systems, and object-detection camera systems.
(2) Description of the Prior Art
Within recent years demands for consumer-used VCR systems have become vast. In accordance with this movement, developments of color cameras became active and a final goal of these developments is to realize a color camera which is very small sized, easy to use and low in power consumption.
The conventional methods to realize signal process parts of the color camera are mainly based on analog signal processing, so that the color camera using the conventional techniques has the following disadvantages:
(A) Analog signals which are converted signals of optical image signals are processed by passing through several analog signal process circuits, so an absolute signal to noise ratio (S/N) of the processed analog signals decays as they propagate from one process circuit to another. For the correction of the S/N decay, very complicated analog circuits requiring many adjustments thereof are needed. This complication decreases the stability and increases the power consumption of the color camera system.
(B) The conventional color camera using a color tube and analog circuits has many adjustment points on the production line. This makes it difficult to manufacture the color camera at a low cost.
(C) The conventional color camera using analog circuits includes very many extra circuit components so as to realize an auto white balanced color correction and an auto gamma correction of the luminance and chrominance signals.
(D) The conventional color camera using analog circuits requires one horizontal delay line as a basic function. This delay line is composed of inductance coils, capacitors, registers and some transistors. This means that it is impossible to fabricate the delay line and the other analog IC's into a monolithic IC chip.
As a summary of the above reasons, the conventional design methods using analog signal processing have their own limit in ability of realizing a color camera which is very small in size, uses mainly IC circuits, is very low in power consumption, is easy to use and very simple to produce.